The present invention relates to a spring-applied, hydraulic pressure released, railway vehicle brake unit and particularly to such brake units that employ positive brake shoe clearance slack adjusters.
Slack adjusters that maintain a positive brake shoe clearance, as opposed to zero clearance slack adjusters, are desirable from the standpoint of brake shoe drag being absent during brake release. Since some means other than the existing brake disc or vehicle wheel must be employed to provide a reference point against which such positive clearance slack adjusters operate, these positive clearance slack adjusters are inherently more expensive than their counterpart zero clearance slack adjusters. This higher cost, however, can be offset by the savings in fuel due to reduced energy consumption in the absence of brake shoe drag, particularly with the high cost of fuel in the industry today.